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Purification of the β product encoded by the Streptococcus pyogenes plasmid pSM19035
Author(s) -
Rojo Fernando,
Weise Frank,
Alonso Juan C.
Publication year - 1993
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(93)80987-6
Subject(s) - plasmid , operon , streptococcus pyogenes , microbiology and biotechnology , biology , isoelectric point , gene product , gene , peptide sequence , biochemistry , genetics , bacteria , gene expression , escherichia coli , staphylococcus aureus , enzyme
Genetic evidence suggests that the gene β product of Streptococcus pyogenes plasmid pSM19035 is required for converting plasmid multimers into monomers. The β protein was purified from cells overexpressing the cloned gene. N‐terminal protein sequence analysis demonstrated that the purified protein had the predicted sequence, except that the N‐terminal initiator methionine was not present. Native β protein consists of a dimer of two identical subunits with a molecular mass of 23.8 kDa (25 kDa in SDS‐PAGE). The β protein (isoelectric point of 9.7) binds specifically to a DNA fragment (312 bp in length) which contains the promoter region of the orf α‐gene β operon and two regions (sites I and II) that show dyad axes of symmetry. It is proposed that protein β binds to sites I and II to mediate resolution of plasmid oligomers.